Method and apparatus for distributed data transfer over multiple independent wireless networks

ABSTRACT

The present invention provides for methods and apparatus for fragmenting a single message and sending the message fragments over multiple independent networks to a single receiving unit. The receiving unit then reassembles the message fragments to generate the original message. The preferred apparatus embodiment is a wireless radio frequency modem that can both receive and transmit fragmented messages over multiple independent networks.

This application claims the benefit of U.S. Provisional Application No.60/227,427 filed Aug. 23, 2000.

FIELD OF THE INVENTION

The present invention is directed to methods and apparatus for wirelesscommunications and more specifically to methods and apparatus fortransferring a single fragmented message over multiple networks to asingle receiving device.

BACKGROUND OF THE INVENTION

New wireless Internet applications continue to drive the need forincreased electromagnetic spectrum utilization in the form of anincrease in bandwidth for transmitting data. Service providers andregulators are simultaneously seeking an equivalent increase in spectrumutilization. To address the above ever-present demands, a variety ofdifferent wireless networks, i.e. Advanced Mobile Phone System (“AMPS”),Global System Mobile (“GSM”), and Personal Communications Service(“PCS”) were developed to transmit data using different frequencies ofthe radio spectrum.

In addition, several technologies have been developed for more efficientuse of the radio spectrum. For instance, Frequency Division MultipleAccess (“FDMA”) is a data transmission technique that allows manycellular telephone users to communicate with one base station byassigning each user a different frequency channel. Code DivisionMultiple Access (“CDMA”) is a technique that enables cellular telephoneusers to share a given frequency channel by breaking each transmittedsignal into many packets of data, each of which is tagged with the cellphone user's code, wherein the packets are spread over a band offrequencies and then reassembled at the receiving end. Cellular DigitalPacket Data (“CDPD”) is another data packet technique similar to CDMA.Orthogonal Frequency Division Multiple access (“OFDM”) is a techniquewherein a data message is split into fragments, and using a singletransmitting source, the fragments are simultaneously transmitted over acluster of (adjacent) radio frequency (“RF”) channels with all channelsusing the same modulation/coding type and controlled by the sameprotocol rules. Finally, Time Division Multiple Access (“TDMA”) is atechnique for channel sharing that assigns each cell phone user arepeating time slot in a frequency channel.

Moreover, the current wireless communications infrastructure asdescribed allows most United States and worldwide cellular regions toprovide for multiple independent standards. Some infrastructure basestation equipment and client side terminal devices, such as cellulartelephones, also have the capability to operate according to multiplestandards. Nonetheless, inefficient utilization of the above-describedcommunications infrastructure occurs for a number of reasons.

First, many client side wireless modem devices operate according to onlyone standard. This is also true for wireline modems. In addition, mostwireline base station equipment is incapable of operating according tomultiple standards because of the more constrictive electromagneticnature of copper wire and coaxial cable used with this equipment.Second, although multiple wireless standards may occupy the same regionand not interfere with each other, these standards typically occupyprincipally the same frequencies in the electromagnetic spectrum, orvery nearly so. This limits a perspective user to one air standard oranother at any given time. Examples include AMPS and CDMA in the samegeographical area or GSM and CDMA in the same geographical area. Inaddition, inefficient utilization may occur due to various interferenceissues among the above cellular techniques, which may also limit aprospective cellular telephone user to one air standard or another, i.e.limiting use to AMPS, which uses CDPD technique or IS-95, which uses theCDMA technique when both are available in the same region.

Finally, the current hardware used to facilitate wireless communicationslimits the utilization of the available bandwidth. One such example ispresently available multimode radio technology, i.e. iDEN/GSM andANALOG/CDMA radios and tri-mode cellular telephones. iDEN/GSM andANALOG/CDMA radios increase the effective footprint of a coverage areaby enabling roaming across multiple technologies, and tri-mode phonescan operate using three different standards. However, each describedunit is only capable of operating according to one standard at a time.

The limitation to one air standard or the other at any given time (in amultiple standard geographic region) prevents both carriers and usersfrom maximizing the utilization of the available infrastructure forwireless data traffic. What is needed are techniques and apparatus thatcan be used to increase utilization of the existing infrastructure andsimultaneously provide users with the greatest possible bandwidth fordata traffic given the existing infrastructure.

SUMMARY OF THE INVENTION

The present invention is directed at addressing the above-mentionedshortcomings, disadvantages, and problems of the prior art. The presentinvention provides for a wireless radio frequency (“RF”) modemconstructed to cooperatively operate with an external message splitcontroller, said external message split controller operative to split amessage into a plurality of message fragments according to one or morepredetermined criteria, and to include with each said message fragmentan identifier of where said message fragment was located within saidmessage, to enable each said message fragment to be transmitted to saidRF modem as a separate electromagnetic signal via a separate selectedtransmitting source over a corresponding selected radio frequency, saidRF modem comprising: an RF front end operative, for each said separateelectromagnetic signal, to receive the signal, to detect the radiofrequency over which the signal was transmitted and to downconvert thesignal to generate a corresponding baseband signal; a basebandprocessing unit coupled to said RF front end and operative to detect anddecode each said baseband signal generated by said RF front end togenerate each said corresponding transmitted message fragment; a centralprocessing unit (“CPU”) coupled to said RF front end and to saidbaseband processing unit, said CPU operative to detect said identifiers;and a message fragment combining unit coupled to said CPU for combiningsaid message fragments as a function of said identifier to generate theoriginal message.

In a preferred embodiment, the modem also comprises a modem messagesplit controller for performing message fragmentation to enable anoutgoing message to be split into multiple message fragments fortransmission over multiple independent networks. Moreover, the externalmessage split controller may be included in a proxy server connected tothe Internet, a network controller for a data communications network ora transmitter controller for a data communications network.

The present invention also provides for a method for transmitting amessage to a single receiving unit over a plurality of independenttransmitting sources, said method comprising the steps of: (a) selectingat least two available transmitting sources for transmitting a messageto an intended receiving unit and selecting a corresponding radiofrequency for each said selected transmitting source; (b) splitting saidmessage into a plurality of message fragments according to at least onepredetermined criteria and including with each said message fragment anidentifier of where said fragment was located within said message; (c)causing each said message fragment to be transmitted to said receivingunit as a separate electromagnetic signal via a separate said selectedtransmitting source over the corresponding selected radio frequency; (d)receiving, in said receiving unit, each said separate electromagneticsignal and extracting the corresponding message fragment; and (e)combining, in said receiving unit, said message fragments as a functionof said identifiers to generate the original message. The messagefragmentation step may be performed according to one or more Quality ofService criteria, including cost, battery life, latency, networkcongestion, and the message fragments may be sent over eitherhomogeneous or heterogeneous networks.

An object of the present invention is to increase the effectivethroughput of a wireless device, to increase utilization of the existingwireless communications infrastructure and to provide users with thegreatest possible bandwidth for transmitting data given the existinginfrastructure, especially in areas where multiple wireless/wirelinenetworks coexist, by simultaneously using those multiple networks tosend a fragmented message to a single receiver unit.

A key advantage of the present invention is that it provides for theaggregation of compatible cellular and wireless Local Area Network(“LAN”) standards in a given cellular region, thus enabling multiple,independent modes of operation in a wireless device to achieve maximumradio efficiency and the greatest possible bandwidth.

Another advantage of the present invention is that the effective datatransmission rate may be increased by an amount proportional to thesubscriber hardware/software capabilities.

Yet another advantage of the present invention is that it enablesnetwork interfacing, i.e., LAN-to-Wide Area Network (“WAN”), WAN-to-LAN,multi-WAN-to-LAN, multi-LAN-to-WAN, multi-LAN-to-multi-WAN andmulti-WAN-to-multi-LAN.

Another advantage of the present invention is that provides for moreeffective communications hardware, such as a universal wireless datamodem. Such a device is useful, for example, for secured communications,for robust data communications, and for large-bandwidth, fixed wirelessapplications.

Still another advantage of the present invention is that it enables highspeed wireless internet data communication applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and the intended advantages of the presentinvention will become more readily apparent by reference to thefollowing detailed description, when taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 illustrates an effective throughput/coverage performance in anexemplary cellular region that can be achieved according to the presentinvention;

FIG. 2 is a diagram showing a parallel multimode operation of a modemdevice according to the present invention;

FIG. 3 is a block diagram of a multimode modem architecture according toone embodiment of the present invention;

FIG. 4 is a flow chart that describes a message fragmentation anddelivery method according to a preferred embodiment of the presentinvention;

FIG. 5 is a diagram illustrating a method for fragmenting a message tobe delivered across three independent networks according to oneembodiment of the present invention;

FIG. 6 is a diagram illustrating how a split message is delivered usingtwo independent networks, where they overlap in the coverage area;

FIG. 7 is a block diagram illustrating the operation of messagefragmentation at a proxy server;

FIG. 8 is an illustration of a method according to the presentinvention, wherein interleaved and transmitted over multiple networks;

FIG. 9 is a block diagram of a preferred embodiment of an RF modemarchitecture according to the present invention;

FIG. 10 illustrates an upconversion methodology when RF front end 930 ofFIG. 9 is implemented; and

FIG. 11 is a block diagram illustrating a RF front end receiverarchitecture according to a preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, a message is split into at least twomessage fragments and each message fragment is sent simultaneously (orsequentially) via multiple independent transmitting sources infundamental ways over several radio frequency (“RF”) channels, using oneor more air interfaces. Although different in fundamental ways, OFDM(Orthogonal Frequency Division Multiple Access) technology is similar tothe present invention in that a given message is split and sent over aselected cluster of RF channels. However, the OFDM technology is not aseffective as the present invention in increasing bandwidth for datatransmission because in OFDM only one transmission source is used, thesame modulation and coding scheme is used by all of the selectedchannels, and a single protocol stack is used by all of the selectedchannels. Whereas, in the present invention, the message fragments aresent via multiple independent sources. Accordingly, the selectedchannels use different signaling schemes, and each network utilized isnot limited by having to operate using the same protocol stack.

Table 1 below illustrates the key difference between the presentinvention and the prior art OFDM technology. OFDM Invention Source ofthe One single source Multiple independent message sourcesModulation/coding The same modulation/ Channels use different typecoding type is used by all (independent) signaling the channels schemesProtocol stack One protocol stack for all Every network may be channelsusing a different protocol stack

Table 1

FIG. 1 illustrates an effective throughput and coverage performance thatcan be achieved according to the present invention. Three independenttransmitting sources (or “networks”) are available in the exemplarycellular region illustrated in FIG. 1: GSM having a data transmissionrate or throughput of D1 bits per second (“bps”); CDMA having athroughput of D2 bps; and CDPD having a throughput of D3 bps. FIG. 1shows that the present invention may be used, for example, to split amessage into three message fragments and to send a different messagefragment via each network. In such a case, the effective throughputwould be the aggregate of the throughput for the individual networks, orD1+D2+D3.

FIG. 2 is a diagram showing a parallel multimode operation of a modemdevice according to the present invention. This device is constructed tooperate in either a LAN or a WAN mode, and supports a plurality ofstandards in each mode, i.e., CDPD, CDMA, GPRS, UWB, and WCDMA in theWAN mode, and Bluetooth, IEEE 802.11 and OFDM in the LAN mode. Theillustrated device according to the present invention is furtherconstructed for simultaneous use of at least two of its compatiblestandards. For instance, the device might operate simultaneously withCDMA and GSM in order to increase the effective bandwidth of the datathroughput to and from the modem device.

Those skilled in the art will realize that other combinations of theavailable standards may be utilized. Moreover, other conventionalstandards and even future wireless or wireline standards may beincorporated for use by the modem device to provide a maximumutilization of flexibility and bandwidth.

FIG. 3 is a block diagram of a multimode modem 300 according to oneembodiment of the present invention. In this embodiment, RF modem 300operates in a receive mode to receive electromagnetic signals carryingmessages, each message including a stream of data bits. RF modem 300also operates in a transmit mode to send electromagnetic signalscarrying messages, each message including a stream of data bits. Modem300 is further operative to receive simultaneously or sequentially amessage that has been split into at least two message fragments, whereineach message fragment includes an identifier of where that messagefragment was located within the message, which enables each messagefragment to be transmitted to the RF modem as a separate electromagneticsignal via a separate selected independent communications network usinga corresponding radio frequency channel. Modem 300 is also operative torecombine the message fragments into the original message.

Modem 300 comprises an antenna 305, a power amplifier 310, a softwareconfigurable direct conversion DSP RFIC 315, a high speed softwareconfigurable CPU ASIC 320, a master clock 325, a Flash memory and SDRAM330, and a fragment combiner and message recovery unit 335. Thesecomponents of modem 300 are electrically connected as illustrated by thesolid lines in FIG. 3 between those components.

Antenna 305, power amplifier 310, clock 325, and memory 330 areconventional components well known on the art. A direct conversion DSPRFIC 315 is an RF front end component that is able to perform RFconversion in the receive mode so as to simultaneously receive at leasttwo message fragments from different transmission sources. DSP RFIC 315is further operative, for each said separate electromagnetic signal, toreceive the signal, to detect the radio frequency over which the signalwas transmitted, and to downconvert the signal to generate acorresponding baseband signal. CPU ASIC 320 is preferably a conventionalcomponent that functions as a controller or processor for modem 300 andalso performs baseband processing and protocol stack control. In thereceive mode, CPU ASIC 320 decodes each baseband signal to generate acorresponding message fragment having a stream of data bits andincluding protocol data bits and then removes the protocol data bits toenable the original message to be recreated. In the transmit mode CPUASIC 320 adds protocol data bits to a stream of data bits correspondingto a message and encodes the data bits into a baseband signal forprocessing by DSP RFIC 315. CPU ASIC 320 is further operative to detectthe identifier in each message fragment. Fragment combiner 335 is also aconventional component used to recombine the message fragments into theoriginal message as a function of the identifier included with eachmessage fragment. Fragment combiner 335 may be integrated within CPUASIC 320 or may be a separate component.

FIG. 4 shows a flow chart that describes a message fragmentation anddelivery method 400 according to a preferred embodiment of the presentinvention. In general, a message to be transmitted to a receiving deviceis split, preferably by a content server, into at least two messagefragments and the message fragments are sent simultaneously via multipleselected transmitting sources (Networks 1 through N which may bepreferred networks according to one or more predetermined criterion)over several radio frequency channels, preferably using different airinterfaces (a heterogeneous transmission technique). The messagefragments could also be sent via multiple transmitting sources using thesame air interfaces (a homogeneous transmission technique). The messagefragments are then reassembled by a receiving device (“terminal”),preferable a mobile device having a wireless RF modem, to generate theoriginal message.

More specifically, after a message intended to be delivered to aterminal is broken into two or more fragments, the fragments arepreferably numbered to facilitate message reassembly at the receiverend. The message fragmentation operation also preferably takes placewithin an externally located content server. In packed data networks,packet numbering is not required. Transmission Control Protocol/InternetProtocol (“TCP/IP”) can be used to perform numbering, but transparently.Each fragment is then carried by a different network.

For example, within a geographic area where both GSM and CDMA networksare deployed, the GSM network may carry the first half of the messagewhile the CDMA network may carry the second half of the message. Thereceiving device is assumed to have the capability of decoding bothhalves of the message and of reconstructing the original message. RFradios may be software configurable to more easily achieve this task.

There are many ways of implementing method 400. A specific example is asfollows. A large streaming video is to be sent by MPEG4 encoding over awireless connection. Assume there are two standards available in aregion. For the purposes of this example, we will also assume thestandards are IS-95B and CDPD, with data rates of 14400 plus 19200 bps,respectively, which are to be combined to obtain an aggregate rate of33600 bps. The image is broken into two parts, with one standardcarrying 14400/33600 or 43% of the data and the second carrying19200/33600 or 57% of the data to obtain the aggregate transfer rate of33600 bps. In other words, the streaming video image data is dividedproportionally to match the data transfer rate of each of the availablechannels in order to obtain the desired increased data throughput. Inthis example, the effective data rate into the receiving device isdoubled by simultaneously using the two networks to transmit the messagefragments. Generally, the potential for increasing the effective datarate at the receiving device is only limited by the networks availablefor transmitting data, if the device is constructed with the requiredsoftware and hardware capabilities.

FIG. 5 is a diagram illustrating a method 500 for fragmenting a messageto be delivered across three networks according to one embodiment of thepresent invention. In this example, a content server 505 splits amessage 501 into three message fragments Frag1, Frag2 and Frag3. Frag1is transmitted via a GSM network. Frag2 is transmitted via an IS-95network, and Frag3 is transmitted via an TDMA network. Device 510,illustrated as a mobile telephone, assembles the message fragments torecreate message 501. FIG. 6 is a diagram illustrating a single messagebeing split into two message fragments and the fragments simultaneouslydelivered via a GSM base station and a CDMA base station, wherein device620, illustrated as a mobile telephone recombines the message fragmentsto generate the original message. The GSM base station and the CDMA basestation overlap in coverage area.

The operation of message fragmentation is preferably performed either bya mobile device (for uplink transmissions) or by a proxy server (fordownlink transmissions). Those skilled in the art will realize that themessage fragmentation operation can also take place at a mobileswitching center a network controller or at a transmitter controller.For the sake of simplicity, only message fragmentation at the proxyserver level is described below.

FIG. 7 depicts the operation of message fragmentation at a proxy serverconnected to the Internet, for example, so that the message can be sentto an Internet Protocol address associated with an intended receivingunit. The proxy server includes an Internet communications adapter and asoftware program executed by the proxy server. A video image is used forillustration purposes. A compressed video image is divided into twofragments. A message split controller is responsible for the messagesplit operation. The size of each fragment is determined depending uponthe available bandwidth on each network selected to transmit the messagefragments.

Other criterion may he considered during the fragmentation process. Forinstance, the message may be fragmented into pieces according to aQuality of Service (“QoS”) criterion, such as latency, cost, requiredpower, battery life, etc. The role of the message split controller is toorchestrate the operation of message fragmentation according topredefined QoS rules. For example, voice signals (less tolerant tonetwork latency) may be sent on a circuit switch network while datafiles (more tolerant to latency) can be sent on a packet switch network.Each message fragment may have a QoS indicator attached to it so thatthe message fragment is sent using a network that satisfies thecorresponding QoS requirement.

Message fragmentation can also be done at a packet level. For instance,multiple packets may be interleaved before being transmitted over thedifferent networks, which can be either homogeneous or heterogeneousnetworks. Interleaving helps equalize the overall system performance interms of latency, packet error rate, coverage, etc. Packet interleavingintroduces diversity into the system.

FIG. 8 illustrates an interleaving table 800 that may be used tofacilitate data transmission according to the present invention.According to the interleaving table illustrated in FIG. 8, packets 1through 40 are ordered row wise and transmitted column wise overNetworks 1 through N. Each column of packets are sent over a differentnetwork. To illustrate the benefits of interleaving according tointerleaving table 800, suppose that Network 1 is a low reliabilitynetwork and that packet 1 was unsuccessfully sent over Network 1.Because of interleaving, packet 1 will be retransmitted on anothernetwork other than Network 1, thereby giving packet 1 an increasedchance of being successfully received on the second try. Without packetinterleaving, packet 1 would have been assigned exclusively tounreliable Network 1 and therefore would take more time than otherpackets to reach its final destination. This would in turn introducebacklog in Network 1 and resultantly cause the message reconstruction atthe receive end to be delayed.

In the FIG. 8 illustration, interleaving is done at the packet level.However, those skilled in the art will realize that interleaving can bedone at a fragment level or even at a bit level.

Referring again to FIG. 7, at the receiver end, the message is simplyreconstructed by reordering all of the received packets. In addition,the selection of which networks to use may be accomplished in a numberof ways. For instance, the receiving unit a monitor a cellular region todetect RF activity relative to multiple channels each supportingdifferent standards. The receiving unit can then report to the proxyserver a list of RF channels detected as well as the air interfacesused. The reported information may be used by the proxy server to splita message and transmit the message fragments in accordance with thatlist. Alternatively, the receiving unit may suggest to the proxy serverto perform message fragmentation according to one or more preferredrules.

Moreover, the list of Existing protocols such as TCP/IP can guaranteemessage fragment ordering without numbering the packets prior to messagetransmission. In the situation where circuit switch networks are used,packets must be numbered according to any conventional numbering ruleprior to transmission, and a mobile device for instance, wouldreassemble the received packets according to the applicable numberingrule. Finally, when the present invention is used in the uplink, i.e.transmit content from a mobile device to a proxy server, the same stepsof the process shown in FIG. 7 take place in the mobile device.

FIG. 9 is a block diagram illustrating an RF modem 900, that can beincluded in a mobile device, capable of message fragmentation accordingto a preferred embodiment of the present invention. Modem 900 comprisesall of the components as illustrated in modem 300 of FIG. 3.Specifically, modem 900 includes a suitable power amplifier device, anRFIC device capable of producing the appropriate baseband signals, and aCPU/ASIC device with suitable memory capable of recovering binary datafrom the baseband signals received from the conversion RFIC device and afragment combiner and message recovery device Modem 900 furthercomprises a message split controller 910 coupled to the CPU/ASIC andused to fragment a message, intended for transmission, according to apredefined rule. Preferably, the rule of message fragmentation andnetwork selection is based on a QoS criterion. These components worktogether to achieve the desired multi-mode packet transfers andaggregation over multiple standards and air interfaces.

The message fragments 1 through N of Message content 905 are generatedby message split controller 910 and passed to base band processor 915,which is preferably software configurable. Baseband processor 915 ispreferably a plurality of baseband processors 1 through N connected inparallel to simultaneously process each received message fragment. Eachfragment is processed according to selected physical layerspecifications. After baseband processing, the data is passed to an RFfront end for up-conversion and transmission. The RF front end for FIG.9 can be implemented in two preferable ways. A conventionalimplementation 920 is based on multiple RF front ends connected inparallel. Each RF front end is used to up-convert a single base bandsignal. An alternative RF front end 930 uses a base band multiplexer931, which is preferably software programmable. The mixed signal is thenup-converted using a single software configurable RF circuit 935.

FIG. 10 illustrates an upconversion methodology 1000 used when RF frontend 930 of FIG. 9 is implanted. Step 1 consists of mixing base bandsignals into a single baseband signal, in this example for simultaneoustransmission over a CDPD network at 800 Mhz, a GSM network at 900 Mhz,and a Bluetooth network at 2.4 GHz. The resulting signal will have aneffective bandwidth equal to the frequency separation between thehighest and lowest frequency signals. Step 2 of the process consists ofup-converting the resulting base band signal to the required frequency.

Methodology 1000 has the unique advantage of being completelytransparent to a carrier as shown by the following illustration. Assumethat an aggregator for providing communications services purchases acertain amount of bandwidth from a number of carriers. Each of thesecarriers may be using a different technology. For instance theaggregator may have a contract with Sprint PCS (using CDMA technology)to use 100,000 wireless phone lines and another contract with AT&T(TDMA) for using another 100,000 wireless phone lines for the purpose ofreselling the SPRINT and AT&T services to its customers at a lower costwith higher throughput. Now assume a customer is equipped with awireless device that can simultaneously decode TDMA and CDMA signals,and the customer wants to download a 1 Mbyte video file to his cellphone. The following steps should take place:

-   -   1. The cell phone sends a request to the aggregator's proxy        server requesting the download of a file and at same time        informs the proxy that its is within coverage of both SPRINT and        AT&T networks. Informing the proxy about the list of networks        within coverage is optional. The proxy may already know by other        means;    -   2. The aggregator's proxy splits the message into two portions,        preferably proportional to the amount of bandwidth available on        the subject networks. Each portion of the message is sent        simultaneously to the cell phone using a different network, e.g.        portion one via AT&T and portion two via SPRINT); and    -   3. The cell phone reassembles the two received data portions        according to a protocol defined between the proxy and the cell        phone.

FIG. 11 is a block diagram illustrates a RF front end receiverarchitecture 1100 according to a preferred embodiment of the presentinvention. RF front end architecture 1100 is suitable for the specialcase when a device is used to send a fragmented message over multipleidentical networks (e.g., all GSM networks or all CDPD networks, etc.).However, architecture 1100 is preferably constructed for use with ahybrid combination of networks. Architecture 1100 comprises a low noiseamplifier (“LNA”) 1105, a high rate analog to digital converter (“ADC”)1110 and a bank of digital 1120 comprising Filters 1 through N connectedin parallel. The components are electrically connected as illustrated inFIG. 11 by the lines between those components.

Architecture 1100 functions as follows. Upon passing through LNA 1105and wherein an intermediate frequency (“IF”) is generated, a largespectrum bandwidth (e.g., several MHz) is down-converted to baseband andsampled using ADC 1110. The rate of ADC 1110 is preferably at leasttwice the size of the down-converted frequency band. digital filter bank1120 is used to tune to the receive frequency of each of the subjectnetworks. Note that the digital filters are identical if the receiver isperforming parallel detection of homogeneous transmitted signals.Homogenous transmitted signals are signals which have a format definedaccording to the same air interface as opposed to heterogeneoustransmitted signals which are signals transmitted according to differentair interfaces. The output of digital filter bank 1120 representsmultiple baseband signals each representing a specific data network. Thebaseband signals are passed to a single (or multiple) basebandprocessors to retrieve the message fragments in a way similar to what isdisclosed in connection with FIG. 4.

The embodiments of the method and apparatus for distributed datatransfer over multiple independent wireless networks described above areillustrative of the principles of the present invention and are notlimited to the particular embodiments described. Other embodiments ofthe present invention can be adapted for use in any RF wirelessenvironment. Accordingly, while the preferred embodiment of theinvention has been illustrated and described, it will be appreciatedthat various changes can be made therein without departing from thespirit and scope of the invention.

1. A method for transmitting a video file to a single receiving unitover a plurality of independent transmitting sources, the methodcomprising: selecting at least two available transmitting sources fortransmitting message fragments of the video file to the receiving unit;splitting the video file into a plurality of said message fragmentsaccording to at least one predetermined criteria and including with eachof the message fragments an identifier of where the message fragment waslocated within the video file; transmitting each of the messagefragments to the receiving unit via a separate one of the selectedtransmitting sources; receiving each transmitted signal at the receivingunit and extracting the corresponding message fragment from the receivedsignal; and combining the message fragments as a function of theidentifiers to reconstruct the video file.